Composite polymer modifiers

ABSTRACT

The invention relates to composite polymer modifiers for thermoplastic resins, and especially for polyvinyl chloride (PVC). The composite modifier is an intimate blend of mineral filler and polymeric process aid, which is formed by the co-powderization of aqueous emulsions, suspensions or slurries of one or more mineral filler(s) and process aid(s). The resulting composite modifier provides more effective modification of the thermoplastic resin than by the use of the dried components formed separately. The composite modifier may also contain other co-powderized components such as impact modifiers, for additional benefits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 13/203,489, filed Aug. 26, 2011, which is anational stage application under 35 U.S.C. § 371 of PCT/US2010/025171,filed Feb. 24, 2010, which claims priority to U.S. ProvisionalApplication No. 61/155,573, filed on Feb. 26, 2009, all of which arehereby incorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The invention relates to composite polymer modifiers for thermoplasticresins, and especially for polyvinyl chloride (PVC). The compositemodifier is an intimate blend of mineral filler and polymeric processaid, which is formed by the co-powderization of aqueous emulsions,suspensions or slurries of one or more mineral filler(s) and processaid(s). The resulting composite modifier provides more effectivemodification of the thermoplastic resin than by the use of the driedcomponents formed separately. The composite modifier may also containother co-powderized components such as impact modifiers, for additionalbenefits.

BACKGROUND OF THE INVENTION

Extruders of rigid PVC compounds and other thermoplastic are constantlyseeking ways to increase output rates through the purchase of largerextrusion equipment, the redesign of existing equipment or the redesignof formulations using new or improved process aids. Improved outputrates result in more economical plant operations that lead to greaterprofitability for the thermoplastic converters.

Thermoplastic formulations contain a variety of additives, includingprocess aids (both conventional and lubricating), and internal andexternal lubricants, designed to increase throughput. Typically externallubricants and certain types of process aids, generically described aslubricating process aids may reduce melt viscosity in PVC formulations.Lubricating process aids are typically low molecular weight polymersthat have a lubricating function built into the polymer backbone.Generally today's rigid PVC formulations are run without lubricatingprocess aids. Conventional process aids typically used in rigid PVCformulations are high molecular weight polymers, with molecular weightssignificantly higher than PVC resin and cause increases in melt torquedepending on their molecular weight.

In WO/093565, Applicant disclosed a method whereby impact modifiers andmineral fillers were co-dried, resulting in a hybrid impact modifierthat overcame problems of dispersion and concentration heterogeneitiesseen when the dry components were blended.

Applicant has now found that co-powderizing aqueous streams or anaqueous blend of polymeric process aids and mineral fillers results in acomposite material in which the dry composite consists of complexparticles that contain both the polymer and inorganic phases in anintimate mixture.

SUMMARY OF THE INVENTION

The invention relates to a composite polymer modifier consisting of:

-   -   a) from 99 to 1 weight percent of one or more inorganic mineral        fillers,    -   b) from 1 to 99 weight percent of one or more polymeric process        aids, and    -   c) optionally from 0 to 80 weight percent of one or more        polymeric impact modifiers,        wherein the total adds up to 100 weight percent, and wherein        said composite polymer modifier is in the form of complex        particles containing both polymer and inorganic mineral fillers        in intimate contact.

The invention also relates to a process of forming the composite polymermodifier involving a) blending aqueous solutions, dispersions,suspensions or emulsions of one or more polymeric process aids with oneor more mineral fillers, which may come in the form of either an aqueousdispersion or a dry powder, and optionally with an aqueous dispersion ofone or more impact modifiers to form a homogenous aqueous blend, andthen b) powderizing said aqueous blend to form composite polymermodifier particles.

The invention further relates to compounds formed by formulating thecomposite polymer modifier into a thermoplastic resin, optionally withother additives.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5, 7 and 8 are Scanning Electron micrographs

FIG. 1. Modifier A (Magnification is 2500×) This is a comparativeexample in which the process aid/impact modifier and mineral filler weredry-blended. The large dark gray spheres are the process aid/impactmodifier. The lighter colored particles on the surface of the acrylicspheres is the CaCO₃.

FIG. 2. Modifier F (Magnification is 500×) This is a comparative examplein which the process aid/impact modifier and mineral filler weredry-blended. The large dark gray spheres are the process aid/impactmodifier. The image shows that when 35% CaCO₃ is post added to theacrylic modifier, there is so much CaCO₃ on the outside of the acrylicmodifier that the acrylic modifier is barely visible.

FIG. 3. Modifier B, of the invention, image is taken before the additionof the flow aid (Magnification is 5000×) When compared to FIGS. 1 and 2,this image shows that even though this product contains approximately35% CaCO₃, the CaCO₃ cannot be seen on the surface of the processaid/impact modifier even at a higher magnification indicating that theCaCO₃ is intimately blended into the process aid/impact modifier.

FIG. 4. Modifier E (Magnification is 500×) Comparative. The image showsthat when CaCO₃ is post mixed with an acrylic process aid, the CaCO₃coats the outsides surface of the modifier.

FIG. 5. Modifier D (Magnification is 2500×) Of the Invention. Whencompared to image 4, this image shows that even though the final powdercontains approximately 35% CaCO₃, the CaCO₃ is not on the surface of theacrylic process aid, but is intimately blended into the process aid.

FIG. 6. Is a plot of Gardner drop dart impact testing, showing synergybetween the intimately mixed CaCO₃ and the acrylic modifier.

FIG. 7. Foamed PVC formulated and extruded using PLASTISTRENGTH 530(Magnification is 100×) Comparative. The image shows the cell structureof a foamed PVC extrudate made using PLASTISTRENGTH 530 acrylic processaid.

FIG. 8. Foamed PVC formulated and extruded using Modifier D(Magnification is 100×) Of the Invention. When compared to FIG. 7, theimage shows that many more foam cells are present indicating that thisnew method of introducing CaCO₃ into a foam PVC compound leads to abetter cell structure.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to composite polymer modifier particles that arean intimate blend of polymeric process aids and inorganic fillers, andalso to a method for producing the composite polymer modifiers by theco-powderizing of aqueous streams of polymer process aids and mineralfillers.

The process aids of the invention are preferably high molecular weightcopolymers that both promote fusion of a thermoplastic into melts thatcan be readily processed, and also alters the melt rheology of thethermoplastic. The process aids are miscible with the thermoplasticresin they will be modifying in the melt state. In one embodiment, twoor more different process aids can be combined.

The acrylic copolymer process aids are present in the thermoplasticcomposition at from 0.1 to 15 weight percent, preferably from 1 to 5weight percent, and more preferably from 2 to 4 weight percent. By“copolymers” as used herein is meant polymers having two or moredifferent monomer units—including terpolymers and polymers having 3 ormore different monomers. The copolymers could be random, block, gradientor of other architectures. The copolymers could be linear, branched, orcrosslinked. The copolymers may contain one or more functional groups,or may be unfunctionalized. “Acrylic copolymers” as used herein, refersto copolymers having 60 percent or more of acrylic and/or methacrylicmonomer units. “(meth) acrylate” is used herein to include both theacrylate, methacrylate or a mixture of both the acrylate andmethacrylate. Useful acrylic monomers include, but are not limited tomethyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate,isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl(meth)acrylate sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, amyl(meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate,cycloheyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, pentadecyl(meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, phenyl(meth)acrylate, benzyl (meth)acrylate, phnoxyethyl (meth)acrylate,2-hydroxyethyl (meth)acrylate and 2-methoxyethyl (meth)acrylate.Preferred acrylic monomers include methyl acrylate, ethyl acrylate,butyl acrylate, and 2-ethyl-hexyl-acrylate, methyl methacrylate, ethylmethacrylate, and butyl methacrylate.

Reactive copolymer process aids may be formed from any monomerscontaining two or more chain reactive chemical groups that can be usedto form branched or crosslinked polymer structure. Useful monomersinclude, but are not limited to (meth)acrylic acid acetoacetoxyalkylesters and amides. Some examples include acetoacetoxyethyl(meth)acrylate(“AAEM”), acetoacetoxypropyl(meth)acrylate,acetoacetoxybutyl(meth)acrylate,2,3-di(acetoacetoxy)propyl(meth)acrylate,acetoacetoxyethyl(meth)acrylamide, 2-cyanoacetoxyethyl(meth)acrylate,2-cyanoacetoxyethyl(meth)acrylamide,N-cyanoacetyl-N-metylaminoethyl(meth)acrylate, and N-(2propionylacetoxybutyl) (meth)acrylamide.

In addition to the acrylic monomer units, the acrylic copolymer of theinvention can also include up to 40 percent of other ethylenicallyunsaturated monomers polymerizable with the acrylic monomers, including,but not limited to styrene, alpha-methyl styrene, butadiene, vinylacetate, vinylidene fluorides, vinylidene chlorides, acrylonitrile,vinyl sulfone, vinyl sulfides, and vinyl suloxides. In one embodiment,the copolymer contains styrene.

In one preferred embodiment the process aid is an acrylic copolymer orterpolymers, with one example being an acrylic terpolymer ofmethylmethacrylate, and butyl acrylate with or without styrene.

The copolymer of the invention generally has a weight average molecularweight in the range of 50,000 to 10,000,000 g/mol, preferably 500,000 to5,000,000. g/mol.

In another embodiment, the acrylic copolymer comprises 10-90 weightpercent of methyl methacrylate units, 10 to 50 weight percent of butylacrylate units, 0 to 50 weight percent of butyl methacrylate units, andfrom 0 to 80 weight percent of styrene, the total adding to 100 percent.

The copolymer of the invention can be made by conventionalpolymerization techniques, including, but not limited to mass, bulk,solution, suspension, emulsion and inverse emulsion polymerization. Theprocess aid will be present in an aqueous form for use in the process toform the composite polymer modifier of the invention, and thereforepolymerization as an emulsion polymer latex, or aqueous suspension arepreferred. The solids content of the aqueous process aid solution,suspension or dispersion is generally between 15-50 percent solids, andmore preferably between 30-45%.

The mineral filler, for use in the invention may be treated ornon-treated, and includes, but is not limited to, ground natural calciumcarbonate (GCC), precipitated calcium carbonate (PCC), nanosized PCC(NPCC), silica (fumed or precipitated), clay, Montmorillonite(nano-clay), zeolite, perlite or any other type of inorganic materialthat can be obtained either as a slurry or as a dry powder. The mineralfiller can also be a mixture of two or more different mineral fillers.

The aqueous mineral filler suspension, dispersion or slurry of theinvention is a water dispersion of mineral filler with a solid contentadvantageously between 5 and 90% by weight, preferably between 40 and80%, This water dispersion can contain any specific surfactant,dispersing agent, additive or filler surface treatment that canadvantageously improve the quality of the slurry (stability, viscosityor compatibility with the host matrix). The composite modifier is formedby co-powderizing an aqueous suspension, solution, or dispersion (latex)of the process aid, and an aqueous slimy of the mineral filler. Theratio of solid process aid to mineral filler solids is dependent on thefinal application, and if other components, such as an impact modifierare also part of the composite modifier. The ratio of process aid tomineral filler is from 99:1 to 1:99, preferably from 75:1 to 1:50.

The blending and powderization can be done in several ways.

Powderization of the aqueous stream(s) can occur by any means known inthe art, including but not limited to spray drying, drum drying,coagulation, freeze coagulation or freeze drying. Following acoagulation step, the composite polymer modifier may be filtered beforedrying.

In a first embodiment, the aqueous process aid and the aqueous mineralfiller dispersion are blended to form a homogeneous aqueous blend. Morethan one process aid(s) and more than one aqueous mineral fillerdispersion(s) can be blended together. This blend is then powderized.

In a second embodiment, the aqueous process aid and aqueous mineralfiller are introduced separately but simultaneously into the dryer andare blended together during the powderization process. Several differentaqueous streams of process aids and/or mineral fillers may be used. Inthe case of spray drying, this blending/powderization can beaccomplished by the simultaneous introduction into the drying chamber ofthe separate aqueous streams through separate nozzles.

In a third embodiment, the aqueous process aid is mixed with a drypowder mineral filler and blended to form a homogeneous aqueous blend.More than one process aid(s) and more than one dry, powder mineralfiller(s) can be blended together. This blend is then converted to apowder.

A combination of the two processes is also contemplated by theinvention, with some or all of each component being pre-blended orblended during the powderization process.

Other aqueous components can also be co-powderized with the process aidand mineral filler in a similar manner. In one preferred embodiment, anaqueous solution, suspension or latex of impact modifier(s) is addedinto the powderization process—either as an aqueous mixture of all three(process aid, mineral filler, and impact modifier) components, orseparately introduced and blended at a point before final drying—such asthrough separate nozzles in a spray dryer.

Impact modifiers useful in the invention, either as part of theco-powderized composite, or added separately include core-shell andlinear copolymer or terpolymer impact modifiers, as known in the art.These are added at from 0 to 80 weight percent based on the polymercomposite modifier. Examples of useful impact modifiers include, but arenot limited to: methacrylate-butadiene-styrene copolymers (MBS),acrylonitrile-butadiene-styrene copolymers (ABS) or acrylic core/shellpolymers (AIM) as well as CPE (chlorinated polyethylene). Thosemodifiers are generally synthesized in water phase through emulsion orsuspension polymerization processes or chlorination of HDPE in slurrystate for CPE preparation. In one embodiment acrylic core shell impactmodifiers are included in the composite polymer modifier.

Whatever the process used to form the composite polymer modifier, thefinal product is considered as a complex polymer modifier being either acomposite modifier when the original mineral part consists in primaryparticles with sizes in the micrometer scale, or a nanocompositemodifier when the mineral part consists in primary particles with sizesin the nanometer scale. The resulting powder material consists incomplex particles that contains both organic and inorganic phases,intimately mixed together, as shown in FIGS. 1-8 (micrographs).

The composite polymer modifiers of the invention are used to modify theproperties of thermoplastic(s) during manufacturing.

Thermoplastics in which the composite polymer modifier of the inventionmay be useful include, but are not limited to alkyl (meth)acrylatepolymers and copolymers, acrylonitrile/butadiene/styrene terpolymers,acrylonitrile/styrene/acrylate copolymers, polycarbonates, polyesterssuch as poly(butylene terephthalate) and poly(ethylene terephthalate),methacrylate/butadiene/styrene copolymers, high impact polystyrene,acrylonitrile/acrylate copolymers, acrylonitrile/methyl methacrylatecopolymers, polyolefins, chlorinated poly(vinyl chloride) (CPVC), andpoly(vinyl chloride) (PVC), polyamides, polyetheresteramides (PEBAX), oralloys of the abovementioned polymers. The thermoplastic polymer canalso be composed of a homopolymer of a vinylidene halide, such as1,1-dichloroethylene or 1,1-difluoroethylene. Biodegradable polymers,such as polylactide or polyhydroxy butyrate are also contemplated by theinvention.

In a preferred embodiment, the thermoplastic is PVC or an alloy thereof,such as PVC/butyl acrylate, used in rigid PVC applications.

Other additives, such as heat stabilizers, internal and externallubricants, other process aids, melt strength additives, other fillers,other impact modifiers, flow aids, and pigments may also be added into afinal thermoplastic formulation. Additional mineral filler, impactmodifier and/or process aid may be added in addition to the amount usedin the composite polymer modifier.

The dried composite polymer modifier is formulated with a thermoplasticpolymer powder, and optionally other additives, by means known in theart—generally as a dry blend of components—and blended until ahomogeneous compound is obtained. The blended compound of compositepolymer modifier, thermoplastic and other additives is then formed intoobjects by conventional melt processing techniques (e.g.: injectionmolding, extrusion, calendaring, blow molding, foaming andthermoforming, etc. . . . ). The composite polymer modifier powder andthermoplastic as a powder or pellets, could also be added together intothe extrusion equipment, however it is more difficult to obtain ahomogeneous blend.

During the admixing, each phase of the modifier (organic and inorganic)is individually dispersed down to their own original primary particlesize into the host thermoplastic matrix. Due to the high compatibilityof the composite polymer modifier with the host thermoplastic matrix,the mineral filler is able to better disperse into this matrix than itusually does when introduced directly as a separate powder.

The composite polymer modifiers of the present invention provide severaladvantages, believed due to the fact that the resultant compositepolymer modifier powder consists of complex particles that contain bothpolymer and inorganic filler phases, intimately mixed together. Theintimate mixture reduces the separation of components during transport,provides increased flowability for the polymer particles, and aids inbetter dispersion of the inorganic mineral filler in the thermoplasticresulting in a more homogeneous modified thermoplastic when compared tothe dispersion of the two powder components added separately into thethermoplastic. Thus there is a clear synergy between the process aid,mineral filler, and optional impact modifier when prepared by theco-powderization process describe in the present invention.

The process for preparing the composite polymer modifier can also beconsidered as a new way of introducing a mineral filler into a plasticmatrix through its intimate combination with an organic process aid,allowing for good dispersion of both standard mineral fillers havingsurface treatments for compatibility with the host plastic matrix, aswell as mineral fillers without any surface treatment. In other words,the polymeric process aid may act as a compatibilizer for the mineralfiller with respect to the host polymer matrix.

The thermoplastic modified by the composite polymer modifiers of theinvention, can be used to manufacture a variety of objects, including,but not limited to: construction products (siding, window profiles,flooring, fencing), pipe, foams, etc. One of skill in the art, based onthe description and examples provided, can imagine a wide-range of usesfor the composition of the invention.

In foam applications, the composite polymer modifier generally containsonly process aid and mineral filler. In foam, the mineral filler(typically CaCO₃) is generally used at about 2 to 20 weight percent, andthe process aid is generally used at about 4 to 14 weight percent basedon the thermoplastic.

In flooring applications, the composite polymer modifier generallycontains only process aid and mineral filler. The mineral filler levelcan be generally from 20 weight percent to as high as 90 weight percentand the process aid is generally used at about 0.5 to 3.5 weight percentbased on the thermoplastic.

In pipe applications the composite polymer modifier may contain impactmodifier in addition to process aid and mineral filler. The mineralfiller level can be generally from 1 weight percent to 45 weightpercent, the process aid is generally used at about 0.5 to 7 weightpercent based on the thermoplastic, and impact modifier is used at from0 to 7 weight percent.

In siding and fence applications the composite polymer modifier maycontain impact modifier in addition to process aid and mineral filler.The mineral filler level can be generally from 2 weight percent to 20weight percent, the process aid is generally used at about 0.3 to 4weight percent based on the thermoplastic, and impact modifier is usedat from 1 to 7 weight percent.

EXAMPLES

The following materials are used in the Examples:

-   PLASTISTRENGTH 530 latex—an acrylic co-polymer of methylmethacrylate    and butyl acrylate (Arkema)-   DURASTRENGTH 320 latex—acrylic impact modifier (Arkema)-   PLASTISTRENGTH 530 process aid (Arkema)-   PLASTISTRENGTH 770 process aid (Arkema)-   CaCO₃ slurry (OMYACARB UF-SY at 75.5% solids in water available from    OMYA)-   PVC resin K67-   PVC Resin K59-   THERMOLITE 140—butyltin mercaptide heat stabilizer from (Arkema)-   THERMOLITE 161—methyl tin heat stabilizer from (Arkema)-   Lubricant 1=calcium stearate as an internal lubricant-   Lubricant 2=lubricant package consisting of hydrocarbon wax, fatty    acid ester, oxidized polyethylene, and polyethylene available from    Honeywell.-   Lubricant 3=paraffin wax with a melting point of 165° F.-   Lubricant 4=oxidized polyethylene wax-   CaCO₃ (GCC, 0.7 microns, used as part of the PVC compound)-   CaCO₃ powder (pcc, 0.07 microns, used as a flow aid for the process    aid/impact modifier)-   TiO2=titanium dioxide

Azodicarbonamide=Exothermic Chemical Blowing Agent

Unless otherwise noted, all percentages are weight percentages, and anymolecular weight is a weight average molecular weight.

Example 1 Modifier A: (Comparative)

294 g PLASTISTRENGTH 530 latex, and 2500 g of DURASTRENGTH 320 latexwere mixed together with an agitator until homogeneous. The blend wasthen spray dried to recover the solids. The resulting acrylic powder hadratio of 10/90 PLASTISTRENGTH 530 to DURASTRENGTH 320. 4 weight percentcalcium carbonate (pcc, 0.07 micron) was added to the recovered powderas a flow aid.

Example 2 Modifier B. (of the Invention)

235 g PLASTISTRENGTH 530 latex, 2000 g of DURASTRENGTH 320 latex, 625 gof CaCO₃ slurry and 384 g of deionized water were mixed together with anagitator until homogeneous. The blend was then spray dried to recoverthe solids. The recovered composite polymeric modifier containedapproximately 35% CaCO₃ with the acrylic portion having a 10/90 ratio ofPLASTISTRENGTH 530 to DURASTRENGTH 320. 4 weight percent calciumcarbonate (pcc, 0.07 micron) was added to recovered powder as a flowaid.

Example 3 Modifier C. (of the Invention)

212 g PLASTISTRENGTH 530 latex, 1800 g of DURASTRENGTH 320 latex, 855 gof CaCO₃ slurry, and 543 g of deionized water were mixed together withan agitator until homogeneous. The blend was then spray dried to recoverthe solids. The recovered composite polymeric modifier containedapproximately 45% CaCO₃, with the acrylic portion have a 10/90 ratio ofPLASTISTRENGTH 530 to DURASTRENGTH 320. 4 weight percent calciumcarbonate (pcc, 0.07 micron) was added to the recovered powder as a flowaid.

Example 4 Modifier D. (of the Invention)

1000 g PLASTISTRENGTH 530 latex, and 264 g of CaCO₃ slurry were mixedtogether with an agitator until homogeneous. The blend was then spraydried to recover the solids. The recovered composite polymeric modifiercontained approximately 35% CaCO₃.

Example 5 Modifier E. (Comparative)

32.5 g PLASTISTRENGTH 530 process aid powder was dry mixed with 17.5 gof calcium carbonate (pcc, 0.07 micron) resulting in a powder thatcontains 65% process aid and 35% CaCO₃.

Example 6 Modifier F. (Comparative)

33.85 g Modifier A powder was mixed with 16.15 g of calcium carbonate(pcc, 0.07 micron). The resulting powder contains 65% process aid/impactmodifier (at a 10/90 ratio) and 35% CaCO₃.

The spray dryer conditions for Modifiers A-D are shown in Table 1: (aNIRO Mobile Minor spray dryer was used)

TABLE 1 Modifier Modifier Modifier Modifier A B C D T_(in) (° C.) 200200 200 200 T_(out) (° C.) 75 75 75 75 Atomizing Air (bar) 2 2 2 2 Jetsweep air (bar) 2 2 2 2 Air sweep T (° C.) 75 75 75 75 Damper Position 00 0 0 Water Flow rate (g/min) 30 30 30 30 Latex rate (g/min) 47.8 54.554.5 54.9 Powder rate (g/min 17.8 24.5 24.5 24.9

Scanning electron micrographs were obtained as follows: The samples werecoated with the Ion Beam Coater with Au/Pd for 10 mins. They were thenimaged with the SEM at 50, 100, 500, 5000, 10000 and 20000×magnification. The Leo 1530 SEM was used for SEM imaging.

Examples 7-9 PVC Substrate Formulations

PVC Substrate Formulations, Examples 7-9, were prepared as follows,using the formulations shown in Table 2;

In a Henschel FM 10 high intensity mixer were added in order (thetemperature increasing due to internal friction):

-   -   a) add the PVC resin and stabilizer to the mixer and turn it on,        heating to 66° C.    -   b) add the lubricants (Lubricant 1 and 2) at 66° C.    -   c) add the acrylic polymer or acrylic polymer/CaCO3 blend        (Modifiers A-C) at 72° C.,    -   d) add the additional CaCO₃ (0.7 micron) at 88° C.    -   e) add the TiO₂ at 98° C.    -   f) mix for an additional 30 seconds, remove the PVC compound        from the mixer and allow to cool.

TABLE 2 parts per hundred resin Formulations 1 2 3 PVC Resin (K 67) 100100 100 THERMOLITE 140 1.0 1.0 1.0 Lubricant 1 1.2 1.2 1.2 Lubricant 21.2 1.2 1.2 Modifier A 4.0 Modifier B 4.0 Modifier C 4.0 CaCO3 (GCC,0.7μ) 15.0 15.0 15.0 TiO2 (Non-chalking) 0.5 0.5 0.5

The PVC compound was formed into a sheet in the following manner: ThePVC compound was added to a Brabender conical twin screw extruder with a6 inch flex-lip sheet die. The PVC compound was extruded into a sheet toa thickness of about 40 mils. The extruder settings used were: Zone 1,172° C.; Zone 2, 176° C.; Zone 3, 183° C.; die 182° C.; screw speed, 35rpm; and feeder setting of 55.

Following cooling of the formed sheet, a dart drop impact test wasperformed using ASTM D 4226, procedure A to calculate the normalizedmean failure energy (normalized mean impact resistance) of each extrudedcompound. The results are shown as a graph in FIG. 6. The graph showsthat as the percentage of CaCO₃ that is intimately mixed with theacrylic modifier (process aid+impact modifier) increases, the normalizedmean impact resistance remains the same even though the percentage ofrubber in the compound is decreasing. As the normalized mean impactresistance would be expected to decrease as the % rubber decreases, itshows that there is a synergy between the intimately mixed CaCO₃ and theacrylic modifier.

Examples 10-11 PVC Foam Formulations

PVC Formulations, Examples 10-11, were prepared as follows, using theformulations shown in Table 3;

In a Henschel FM 10 high intensity mixer were added in order (thetemperature increasing due to internal friction):

-   -   g) add the PVC resin and stabilizer to the mixer and turn it on,        heating to 66° C.,    -   h) add the lubricants (Lubricant 1, 3, and 4) at 66° C.    -   i) add the process aid at 72° C.    -   j) add the additional CaCO₃ (0.7 micron) and azodicarbonamide at        88° C.    -   k) add the TiO₂ at 98° C.    -   l) mix for an additional 30 seconds, remove the PVC compound        from the mixer and allow to cool,

TABLE 3 parts per hundred resin Formulations 4 5 PVC Resin (K59) 100 100THERMOLITE 161 3.0 3.0 Lubricant 1 0.7 0.7 Lubricant 3 1.0 1.0 Lubricant4 0.15 0.15 PLASTISTRENGTH 530 10.0 Modifier D 10.0 PLASTISTRENGTH 7702.0 2.0 CaCO3 (GCC, 0.7μ) 5.0 5.0 TiO2 (chalking) 4.0 4.0Azodicarbonamide 0.35 0.35

These compounds were extruded using a Brabender ¾″ 25:1 L/D single screwextruder with a rectangular (2″×⅛″) profile die. The extruder settingsused were: Zone 1, 181° C.; Zone 2, 181° C.; Zone 3, 181° C.; die 178°C.; screw speed, 75 rpm. Extrudate samples were collected and cooled ina water bath. The SEM images shown in FIGS. 7 and 8 were generated fromthese samples to show differences in the cell structure.

What is claimed is:
 1. A composite polymer modifier consisting of: a)from 99 to 1 weight percent of one or more inorganic mineral fillers, b)from 1 to 99 weight percent of one or more polymeric process aidswherein said one or more process aids is an acrylic copolymer includingone or more acrylic monomers selected from the group consisting ofmethyl acrylate, ethyl acrylate, butyl acrylate, 2-ethyl-hexyl-acrylate,methyl methacrylate, ethyl methacrylate, and butyl methacrylate andhaving a molecular weight of 50,000 to 10,000,000 g/mol, and c)optionally from 0 to 80 weight percent of one or more polymeric impactmodifiers, wherein said one or more polymeric impact modifier isselected from the group consisting of core-shell impact modifiers, andlinear copolymer impact modifiers, wherein the total adds up to 100weight percent, and wherein said composite polymer modifier is in theform of powdered, substantially homogeneously blended complex particlescontaining both polymer and inorganic mineral fillers in intimatecontact, and wherein said composite polymer modifier is formed by aprocess comprising the steps of: a) blending aqueous solutions,dispersions, suspensions or emulsions of said one or more polymericprocess aids with said one or more mineral fillers which may be in theform of either an aqueous dispersion or a dry powder, and optionallywith an aqueous dispersion of said one or more impact modifiers to forma homogenous aqueous blend, and b) powderizing said aqueous blend toform said composite polymer modifier.
 2. The composite polymer modifierof claim 1, wherein the ratio of said one or more polymeric process aidto said one or more mineral filler is from 75:1 to 1:50.
 3. Thecomposite polymer modifier of claim 1 wherein said acrylic copolymer isan acrylic copolymer including one or more acrylic monomers selectedfrom the group consisting of methyl methacrylate, butyl acrylate, butylmethacrylate, ethyl acrylate, and further optionally including styrenepolymerizable with the acrylic monomer.
 4. The composite polymermodifier of claim 1 wherein said one or more impact modifier is selectedfrom the group consisting of methacrylate-butadiene-styrene copolymers,acrylonitrile-butadiene-styrene copolymers, and acrylic core/shellpolymers.
 5. A composite polymer modifier consisting of: a) from 99 to 1weight percent of one or more inorganic mineral fillers wherein said oneor more mineral fillers is untreated, b) from 1 to 99 weight percent ofone or more polymeric process aids wherein said one or more process aidsis an acrylic copolymer including one or more acrylic monomers selectedfrom the group consisting of methyl acrylate, ethyl acrylate, butylacrylate, 2-ethyl-hexyl-acrylate, methyl methacrylate, ethylmethacrylate, and butyl methacrylate and having a molecular weight of50,000 to 10,000,000 g/mol, and c) optionally from 0 to 80 weightpercent of one or more polymeric impact modifiers, wherein said one ormore polymeric impact modifier is selected from the group consisting ofcore-shell impact modifiers, and linear copolymer impact modifiers,wherein the total adds up to 100 weight percent, and wherein saidcomposite polymer modifier is in the form of powdered, substantiallyhomogeneously blended complex particles containing both polymer andinorganic mineral fillers in intimate contact, and wherein saidcomposite polymer modifier is formed by a process comprising the stepsof: a) blending aqueous solutions, dispersions, suspensions or emulsionsof said one or more polymeric process aids with said one or more mineralfillers which may be in the form of either an aqueous dispersion or adry powder, and optionally with an aqueous dispersion of said one ormore impact modifiers to form a homogenous aqueous blend, and b)powderizing said aqueous blend to form said composite polymer modifier.